Hardly any one of us has ever seen a molecule, and unless we have studied a lot of chemistry and physics and physical chemistry, we probably don't understand the tests and criteria used by scientists to detect molecules, analyze them, identify them or describe their structure. Still, we believe they exist, have definable structures, weights and shapes possess predictable properties. We have been taught that all molecules are made up of a hundred or so elemental atoms - just as all words are made up of the same basic letters. The countless and varied molecules that make up our physical world differ from each other only with respect to the type of atoms they contain, the numbers of atoms present, their pattern of organization and their location in the molecular structure - just as all of the words in our language differ from each other only with respect to the letters they contain and their sequence. And the same words can be used to write a psalm or a political pamphlet - just as the same molecules can be found in an ant or an elephant.

There is nothing mystical about this anymore. It isn't imaginary or hypothetical. The concept of molecules and atoms and their reactions is as accepted as are things we can see and judge with our own senses.

If a chemist tells us that a given molecule has three carbon atoms and another molecule has six, we believe him. If the chemist tells us that the six carbon atoms of one molecule are in a ring, while in another molecule they are forked, we believe him. Sometimes we believe because it makes sense. More often, we believe because we have no reason to disbelieve. Most of the time we believe because we have a basic confidence in the chemist's honesty and competence.

Chemists and their colleagues have more credibility in our eyes than merchants, lawyers and most of the public servants we choose to run our country. And much of the confidence is justified. Molecular theory and manipulation are the very basis of the exciting discoveries being made almost daily in physiology, genetics, microbiology and pharmacology. The chemist has used his molecular models quite effectively to make predictions and products that have changed our lives.

For example, people long ago discovered, by empirical trial and error, that certain foods were nutritious while others were poisonous; certain beverages were intoxicating while others were innocuous; certain diets were fattening white others, which also satisfied hunger, were less so. In the early years of this century nutritionists learned that the absence of certain foodstuffs from normal diets resulted in pathological consequences. About the same time, allergists learned that adding certain ingredients to normal diets also resulted in pathological consequences. It wasn't until the chemists provided us with "metabolic maps" that we started to sort out the mass of confusing empirical data. These metabolic maps described the molecular pathways involved in food digestion and cell synthesis. They showed how the complex minerals, proteins carbohydrates and lipids present in our foodstuffs could be broken down into simpler and simpler molecules; concurrently, these simple molecules could be utilized by our own bodies for putting together the proteins, minerals, carbohydrates and lipids that constitute our tissues. The maps showed how the whole process was regulated by other molecules (vitamins). The molecular models explained how and why certain foods generated toxic responses and other foods generated allergic responses; the bases of some classical deficiency diseases like rickets, pellagra, goiter and beriberi; the rationale of weight-reducing diets; and dozens of other physiological and pharmacological phenomena.

It can be fairly said that molecular chemistry and molecular biology established nutrition, physiology and nutritional pathology as sciences and took them out of the grasp of alchemists and quacks.

Kashrut and ChemistryThoughts of this nature kept intruding as I was reviewing the Torah portion Semini (Leviticus 9-10), wherein the Jewish people were commanded, eternally, to avoid certain foods while being permitted to consume others.

The Torah itself gives no reason for these laws. But anyone familiar with the modern molecular theories of nutrition and nutritional pathology can hardly avoid the temptation of creating molecular models and maps to explain everything in this field.

But it is futile speculation...

In his classic volume on biblical and talmudic medicine, written 73 years ago. Dr. Julius Preuss introduced his discussion on kashrut (dietary laws) with the following statement:

The biblical dietary laws are included in the chapter on "Hygiene" solely because we can conceive of no reason other than sanitary for their ordination. It must be emphasized, however, that the Torah gives us no reason at all for these laws and the later sources do so only rarely. Thus, nearly everything which one alleges to be the reason for the dietary laws is only a hypothesis and is read into the sources...

This statement establishes precisely the frustrating paradox confronting anyone who would like to explain the laws of kashrut using modern knowledge of nutrition and public health as a model. We don't know why certain animals, birds and fish are permitted for food while others are banned; we don't know why the permitted quadrupeds and birds must be slaughtered in a given fashion; we don't know why blood, certain fatty tissues and the sciatic nerve are forbidden; we don't know the hazards associated with cooking and/or consuming meat and milk; and we don't know why certain specific anatomical imperfections render an animal or fowl traifa (not kosher) and thus prohibited. We are provided with remarkably detailed guides and instructions about the criteria that distinguish between prohibited and acceptable, but nothing about why. Though we very much want to know why, any rational explanation is simply an exercise in human imagination.

The greatest minds ever produced by the human race have struggled for thousands of years to explain these laws. Dozens, if not hundreds of hypotheses have been proposed to elucidate these mysteries. Why is the ox kosher and the camel not? Why can't a Jew eat pork and benefit from the well-known nutritional quality of swine flesh? Why is carp acceptable while eels are not? The rational mind yearns to understand and unfortunately, because it cannot understand, sometimes decides to ignore the laws altogether!

In the last hundred years or so, it has become fashionable to explain kashrut with analogies from public health. The basic argument is that Moses was really a primitive health commissioner, and the Parshah of Shemini was an early model of current Pure Food and Drug laws. It is an intriguing concept, but its adherents today are mainly Jews who do not want to observe the dietary restrictions in the first place. Very little support for this point of view will be found in authentic public health research. Rabbits are as nutritious as chickens; gefilte fish can be made as well from sturgeon as from trout; there isn't that much difference - microbiologically or chemically - between lamb and pork.

It would be easier to understand (and adhere to?) the dietary restrictions if we would find a chemical reason. It would be easier particularly if we could isolate some kind of substance or harmful chemical from a forbidden food that is not present in a permitted food. Or if we could show that the processes described in the Shulchan Aruch (Code of Jewish Law) inhibit some obscure molecular reaction which produces a toxin. That would make sense. We have a lot of empirical experience with food poisoning and allergies. Undoubtedly our ancestors did also. There are certain foodstuffs in nature that are intrinsically poisonous - certain mushrooms, for example, some fish and some mollusks. It would be quite reasonable for a primitive lawmaker to ban them as food for his tribe. We also know that foods, if improperly stored or processed, can become vehicles for transmission of infectious agents or their toxins. Thus a primitive lawgiver, concerned with the physical health of his tribe, would also ordain laws about processing and storing the materials which have been permitted as food.

If non-kosher foods or improper processing resulted in food poisoning or infection or skin eruptions, we could understand.

But they really don't. From a nutritional and toxicological perspective, there is no difference between kosher and non- kosher diet. The answer certainly is not chemical. It isn't the physical atoms and molecules of pork that render it inedible for Jews. Otherwise, why is it not forbidden to non-Jews? Is it possible that there are chemical receptors or Jewish cells that are sensitive to molecules of traifa foods? It is not beyond medical experience. Some humans are allergic to strawberries while others are not. Indeed, the only difference between the allergic and the retractile is a subtle molecular reaction that occurs in the former and not in the latter. A better example might be the genetic (some say racial) inability of some humans to digest bovine milk while others literally thrive on it. Thus there are molecular reactions, in the realm of nutritional pathology and which are hereditary that can serve as a justification for dietary taboos.

Unfortunately, it doesn't wash clean. Jewish racial qualities are more a Nazi myth than a chemical reality today. When the dietary prohibitions were announced, the 12 tribes encamped around Sinai several thousand years ago certainly shared a similar genetic make up. But in the thousands of years since then and particularly in the thousands of years of diaspora, the genetic homogeneity became significantly diluted. Jews today differ greatly in blood types and immunological make up and physiological response to nutrients. Today a chemical explanation of kashrut - which remains extremely binding despite the gradual genetic diversification is - simply an inadequate hypothesis. A convert to Judaism is obligated to observe the kashrut laws as soon as she or he becomes a Jew, even if he or she has thrived physiologically on the now-forbidden foods until that very moment.

Spiritual MoleculesMany of the rabbinic commentators make reference, while humbly denying that they know the true answer, to the "spiritual damage" that derives from non-kosher foods. For example. Rabbi Shimshon Raphael Hirsch comments on the Torah portion Kedoshim (Leviticus 19-20) as follows:

You must... conscientiously keep... the choice of nourishment... as the very first preliminary... for spiritual, mental and moral clarity, purity and holiness... right from the beginning, at the actual forming of the tissues of your body, the physical formation of the fibers of your brain, nerves and muscles...

The forbidden foods are thus not materially poisonous, but they are harmful to our soul. The dangerous components of pork cannot be detected by chemists, and the toxicological effects of its consumption cannot be diagnosed by physicians, but the damage does certainly occur. If we want to think in terms of molecules, we must think about "spiritual molecules".

In this respect, I once read that there are spiritual poisons in certain proscribed foods that dull the spiritual senses or, as is put so well in Yiddish, "stuff up the nose and ears of the soul" to the extent that the individual can no longer receive spiritual messages. I also heard that the animals forbidden as food by Torah possess certain spiritual characteristics which the consumer is in danger of acquiring. Whatever the rationale, spiritual molecules make more sense than chemical ones.

But they make sense only to one who already believes in the authority of Torah and that person is already willing to obey the rules without any rationalizations. To the rest of the world, spiritual molecules are too much the subject of mystery and superstition. In the spiritual realm, according to those who consider themselves modern and scientific there are no rules and no logic - just a lot of fairy stories, visions, magic, witchcraft and gurus.

Of course, real molecules are also invisible and intangible to most of us. Real molecules are also the subjects of speculation by the gurus (of science) who wear their priestly garments and who officiate in their esoteric temples (called laboratories) after years of apprenticeship. But spiritual molecules are too much for the twentieth century.

(Parenthetically, I wonder if our rabbis would be more successful in getting their message across if they exchanged their black frocks for white lab coats? I wonder if the observance of kashrut would be enhanced by impressive lab equipment and periodic tables and diagrams of covalent electron bonds or their spiritual equivalent? Probably not. The contemporary Jewish non-observer is too sophisticated for that; he wouldn't fall for such gimmicks. If he doesn't obey the rules when G-d Himself issues them, why would he change because a rabbi put on a white coat?

Then why does he believe in molecules made up of carbon atoms? But that's another story...)

I submit that the real barrier to accepting the role of spiritual molecules derives from two handicaps in conceptualization:

1) The lack of immediate empirical proof of spiritual harm when the laws are disregarded;

2) The matter of particularism, i.e. the selective nature of the dietary laws which permit the majority of humans to eat and benefit from a given food while denying the same opportunity to a very small group of people who are indistinguishable in any detectable way from the majority and who also seem to benefit from the food.

PKU - a Medical Model of Kashrut?

We are taught in Chassidism that the spiritual world and the material world are parallels of each other. Thus phenomena experienced in the flesh and blood universe are modeled on spiritual phenomena. Similarly, the spiritual universe is reflected in things and events which are detected by our mortal senses.

This permits us to postulate the existence of spiritual molecules based on our knowledge of chemical structures. Indeed, there are those who would say that the material molecules we study and teach about in chemistry courses are really the reflection of the intangible spiritual molecules the Creator used as a blueprint!

With this in mind I present the natural history of a rare genetic disease that might provide some kind of answer to those who reject kashrut because they lack empirical proof of harm and feel uncomfortable with strict particularism.

Medicine is familiar with a condition called phenolketoneuria or PKU. First described fifty years ago, this hereditary metabolic disorder affects about one out of 15,000 children born in the northern hemisphere and leads, among other things, to an irreversible and severe retardation.

The newborn child appears healthy and normal. He cannot really be distinguished during a routine physical examination, from his 14,999 unaffected peers. He has a normal appetite and an apparently unremarkable metabolism. He eats, sleeps, cries and does all of the other things babies are expected to do. But gradually - over the course of several years - he develops a characteristic appearance and brain damage.

Many years after the disease was first described, physiologists determined that the brain damage was a result of the accumulation in the body of a certain amino acid - phenylalanine - which is a common molecule in many proteins. Normal people have the ability to metabolize phenylalanine and to convert it to other, non-harmful (and essential) nutrients. But one child in 15,000 lacks the necessary enzyme and the phenylalanine accumulates and accumulates until it harms the developing brain.

About 35 years ago, a chemist named Guthrie described a blood test which permits the early diagnosis of PKU, within a few days after birth, long before the neurological damage has occurred. This test is now compulsory in most Western countries (including Israel). Every baby born in a hospital is tested for PKU. If the results suggest that the condition is present, the mother is provided with nutritional advice and counseling. If the diet is modified early enough, if the phenylalanine-containing protein is replaced with a synthetic substitute and fed for the first four or five years, the retardation can usually be avoided. The solution isn't simple; it is also inconvenient, unappetizing and expensive. But, it is effective.

Now consider the following scenario: a public health nurse visits a young mother who has just come home from the hospital with her precious newborn baby. The nurse conveys the frightening news that according to the lab tests the baby has PKU. She also provides the mother with a list of prescribed foods and instructions for preparing a suitable preventive diet.

Neither the nurse nor the mother is a chemist. The mother knows nothing about molecules or physiology or metabolism. She knows what she sees - a healthy, normal baby, like any other baby in the world, who enjoys eating and is apparently thriving on the diet being provided. The nurse knows a little more. She has studied a little chemistry and understands the best physiology of metabolism. Or at least, she believes the teachers who taught her. The nurse doesn't really know the basis of the diagnostic tests; nor could she prescribe a diet out of her own experience. All she is doing is her job of transmitting the information she was taught. She believes she is acting in the best interests of the child and the community. But she is mostly acting out of duty and acceptance of higher authorities - such as doctors, chemist and nutritionists - who have studied more and know more and have better sources of knowledge.

The mother refuses to accept the diagnosis or the diet. She doesn't believe in the mysteries of chemistry or accept the authority of the doctors. Doesn't her baby look normal? Isn't the baby happy? Besides, the recommended diet is too expensive and inconvenient and unappetizing. What is all this nonsense about molecules anyway?

I end with the following question:

If you were the nurse, what would you do when the mother demands, "Show me the danger now! Show me the difference between my baby and all the others!